The aerodynamic design of modern aircraft is a compromise between many conflicting requirements, thus limiting near optimum aerodynamic performance to a small portion of the aircraft flight envelopes. In the use of mission adaptive wing technology, sizable improvements in payload range, maneuverability, and ride quality are made possible.
One technical approach to the mission adaptive wing involves the use of variable camber leading and trailing edge flaps having smooth upper surface flexible panels. The panels are adapted to change shape when the flaps are deflected during flight. It is of particular interest to adapt the mission adaptive wing to a variety of wing planform geometries.
Specifically, in the area of wing tips, compound curvature prevents the use of a prior art basic variable camber actuation system, and a more sophisticated method of closing out a wing leading edge flap is required. Whereas a variable camber wing tip is not specifically required for a fixed wing application, it is a definite requirement for a variable sweep wing, and is aerodynamically desirable for fixed wings using variable camber leading edges.
The only known prior attempt to make a variable camber wing tip was in the form of a solid plug deflectable with respect to the surrounding wing structure. This type of wing tip presented large discontinuities between the tip and adjacent wing structure in all deflected positions. The large discontinuities resulted in high drag to the extent that the wing tip design was considered to be unsatisfactory.
A search of the patent literature discloses a number of variable camber wing structures which are not directly pertinent. French Pat. No. 568,605 illustrates a variable camber wing that does not have a compound curvature in the deflected position. Similarly, U.S. Pat. No. 1,747,637 teaches a variable camber wing that is increased in thickness when the camber is increased but it also does not teach a compound curvature.
The following patents disclose various forms of wing structures:
U.S. Pat. No. 1,203,558 PA1 U.S. Pat. No. 1,567,531 PA1 U.S. Pat. No. 2,022,806 PA1 U.S. Pat. No. 2,820,601 PA1 U.S. Pat. No. 3,152,775 PA1 Italian Pat. No. 251,868 PA1 1. It eliminates the drag problems of the prior art. PA1 2. It provides extremely good contour capability with adjacent structure at all flap positions. PA1 3. It is adaptable to any variable camber leading edge application. PA1 4. It has a simple but rigid structure due to the number of scissor plates. PA1 5. It is not dependent on wing planform or size. PA1 6. It is capable of subsonic and supersonic applications. PA1 8. It is suitable for trailing edge variable camber flap closeout.